fix(query): avoid panic on UInt64 full-range scan stats (#19555)

[sundy-li]

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Summary

• avoid the UInt64 full-range overflow when Scan::derive_stats reduces NDV from min/max column statistics
• keep the planner on the saturating path for [0, u64::MAX] stats instead of panicking during scan stats derivation
• add a sqllogictest regression for the full-range UInt64 table case

Fixes #19555

Implementation

1. Extract the integer-range NDV reduction into a helper in scan.rs
2. Use saturating arithmetic for unsigned spans so max - min + 1 does not overflow on the full UInt64 range
3. Add a unit test for the helper and a sqllogictest regression covering the reported table shape

Tests

• Unit Test
• Logic Test
• Benchmark Test
• No Test - Pair with the reviewer to explain why

Validation run locally:

• CARGO_HOME=/workspace/databend/.worktrees/pr-fix-19555/.cargo-home CARGO_TARGET_DIR=/workspace/databend/.worktrees/pr-fix-19555/.cargo-target cargo test -p databend-common-sql test_reduce_ndv_by_uint_full_range_saturates
• CARGO_HOME=/workspace/databend/.worktrees/pr-fix-19555/.cargo-home CARGO_TARGET_DIR=/workspace/databend/.worktrees/pr-fix-19555/.cargo-target cargo clippy -p databend-common-sql --tests -- -D warnings

Added but not executed locally:

• tests/sqllogictests/suites/base/issues/issue_19555.test

Type of change

• Bug fix (non-breaking change which fixes an issue)

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This change is 

[sundy-li]

Closing this PR because the same fix was already merged via #19632 on 2026-03-30. As a result, this branch now has no net diff against main.